Airbag unit comprising a retaining element and supporting element for fixing the airbag

ABSTRACT

The invention relates to an airbag unit comprising an airbag ( 3 ) and a flat supporting element ( 2 ), whereby the air bag ( 3 ) is situated in front of a surface ( 21 ) of the supporting element ( 2 ), and the supporting element has an opening ( 20 ) for fixing the airbag ( 3 ) thereto. The airbag unit also comprises a retaining element ( 1 ) that, for fixing the airbag ( 3 ) to the supporting element ( 2 ), interacts therewith. A section ( 32 ) of the airbag ( 3 ) passes completely through the opening ( 20 ) of the supporting element ( 2 ) to the other side of the supporting element ( 2 ) and is held there in front of the other surface ( 22 ) of the supporting element ( 2 ) by means of the retaining element ( 1 ). The dimensions both of the opening ( 20 ) of the supporting element ( 2 ) as well as of the retaining element ( 1 ) are matched to one another whereby enabling the retaining element ( 1 ) to be guided through the opening ( 20 ) in a first spatial orientation, and an edge area of the opening ( 20 ) prevents the retaining element ( 1 ) from moving in at least one second spatial orientation of the retaining element ( 1 ).

The invention relates to an airbag unit according to theprecharacterizing clause of claim 1.

An airbag unit of this type is part of an airbag module which is used inmotor vehicles to protect an occupant in the event of a crash. Itcomprises an airbag which can be inflated by means of a gas generator; aflat supporting element, in front of whose one surface the airbag isarranged and which has an opening for fixing the airbag on thesupporting element; and a retaining element which interacts with thesupporting element in order to fix the airbag thereon.

DE 296 06 724 discloses an airbag module for a vehicle, in which theairbag is fixed with the aid of a fastening frame, two bolts with a nutand washer and a fastening tape and is connected to a gas generator. Thefastening frame is introduced into the airbag and positioned within theairbag in such a manner that, firstly, the inflow opening of the airbagand a corresponding opening of the fastening frame are arrangedcongruently and, secondly, two openings in each case in the airbag andfastening frame for the screw connection are arranged one above another.The fastening frame with the airbag is designed in such a manner that,after this first subassembly is connected to the gas-generatorsubassembly, the inflow opening of the airbag and the outflow opening ofthe gas generator overlap each other. The preassembled gas-generatorsub-assembly is formed by putting together a gas generator, a fasteningtape and a covering plate for a second outflow opening of the gasgenerator.

The invention is based on the problem of providing an airbag unit whichcan easily be installed and makes it possible with simple means toreliably fix the airbag on a supporting element of the airbag unit.

This object is achieved according to the invention by the provision ofan airbag unit having the features of patent claim 1.

In accordance therewith, one section of the airbag extends through theopening of the supporting element to the other side of the supportingelement and is retained there in front of the other surface of thesupporting element by means of the retaining element. The dimensions ofthe opening of the supporting element and of the retaining element areselected in such a manner that the retaining element can be guided alonga lead-through axis through the opening of the supporting element in afirst spatial orientation. In a second spatial orientation, whichcorresponds in particular to an alignment essentially transverse withrespect to the first spatial orientation, the retaining element cannotbe guided through the opening of the supporting element. The edge regionof the opening of the supporting element and surface elements of theretaining element then bear against one another.

In the solution according to the invention, the simple positioning andfixing of the airbag on the supporting element is of advantage. Theinstallation is possible without additional mechanical auxiliary devicesand a removal of defective components can easily be carried out.

The retaining element is preferably held within an interior space formedby the associated airbag section.

As an alternative, the retaining element can merely be clasped by theairbag section.

The supporting element and the retaining element are designed andarranged in such a manner that the retaining element reaches in aform-fitting manner behind the opening in the supporting element andthat, during an airbag release in which the airbag unfolds because ofthe gas produced by the gas generator flowing into it, the retainingelement which is clasped or held by the airbag section is pressedagainst the supporting element.

During the airbag release, the airbag unfolds because of the gasproduced by the gas generator flowing into it, and the forces whichoccur in the process and act in the airbag unfolding direction partiallypull the airbag section through the opening of the supporting element,in which case the retaining element, which is partially clasped or heldby the airbag section, is pulled in the direction of the unfolding ofthe airbag. In the process, the retaining element is pressed against theedge of the opening of the supporting element because of the geometrywhich has been selected. The tensile forces which are produced by theunfolding of the airbag and act on the retaining element therefore bracethe retaining element and the supporting element against each other, inwhich case further pulling of the airbag section through the opening ofthe supporting element is prevented by the retaining element, and theairbag is retained on the supporting element.

The retaining element is expediently designed as a small plate havingsuch a thickness and edge length, and the opening of the supportingelement is expediently of slot-shaped design with such a slot width andslot length that the thickness of the small plate is smaller than theslot width and at least one edge length of the small plate is smallerthan the slot length of the supporting element. However, the retainingelement and the opening of the supporting element may also be formed inaccordance with other geometrical shapes.

In one preferred embodiment of the airbag unit, the retaining element isprovided with a throughflow opening and the airbag is provided with aninflow opening in the region of the airbag section, said openings beingarranged adjacent to the opening of the supporting element.

The airbag unit according to the invention can advantageously be used inthe case of an airbag module in which a gas generator having an outflowopening is arranged in such a manner that the inflow opening of theairbag and the outflow opening of the gas generator overlap each other.During the airbag release, the gas produced by the gas generator canthus flow directly into the airbag in the region of the fastening pointat which the airbag is fixed on the supporting element.

For the defined positioning of the retaining element in the airbag unitand with respect to the gas generator, a tubular, in particularcylindrical element is preferably arranged in such a manner that itprotrudes through the throughflow opening of the retaining element andthe opening of the supporting element. The positioning of the retainingelement, of the airbag section, of the supporting element and of the gasgenerator with respect to one another is thereby facilitated and tiltingof the retaining element is prevented. In order to conduct the gas intothe airbag, the tubular element has a gas outlet in the form of a tubeopening.

In one variant of the invention, the tubular element is arranged on theoutflow opening of the gas generator and protrudes through the inflowopening of the airbag, the throughflow opening of the retaining elementand the opening of the supporting element. The tube opening leads intothe airbag in order to enable the gas to flow in during the airbagrelease. The risk of an escape of gas and/or of a displacement of theretaining element by the compressive forces on the retaining elementthat occur during the blasting of the gas into the airbag is avoided.

In a further variant, the tubular element is arranged on the throughflowopening of the retaining element and protrudes with the tube openingthrough the opening of the supporting element into the airbag, thethroughflow opening being positioned together with the tubular elementon the outflow opening of the gas generator.

Other geometrical shapes of an element for positioning the retainingelement in the airbag unit and with respect to the gas generator arealso conceivable. Furthermore, the element may, for example, also be ofshorter design and may not protrude into the airbag.

In one embodiment, the supporting element is part of a housing which atleast partially surrounds the gas generator and thereby positions theretaining element together with the airbag with respect to the gasgenerator. The housing and the gas generator are secured with respect toeach other by screw connections. The housing may subsequently be usedfor fastening the airbag module in the vehicle.

In order to position and hold the airbag unit and the gas generator, amulti-part retaining device which has two hose clips may advantageouslybe used. The hose clips at least partially surround the gas generatorand hold the supporting element, which is of essentially flat design, ata defined distance from the gas generator. Furthermore, the hose clipshave apertures for holding the supporting element and are supported onthe gas generator.

The hose clips are arranged on both sides of the outflow opening, alonga direction of extent of the supporting element, and in each casecontain an aperture for holding the supporting element, the supportingelement having bending sections on its end sections. The bendingsections protrude out of the apertures and are bent essentiallytransversely with respect to the apertures, so that the bending sectionssecure the supporting element on the hose clips.

Rapid and simple installation of the airbag unit and gas generator andalso a low weight are advantageous in this embodiment.

One advantageous development of the invention is achieved by theretaining device having at least one fastening element which secures thegas generator on the supporting element and surrounds the gas generatorin the region of the outflow openings in such a gastight manner that achamber leading into the airbag is formed. This enables a simpleinstallation to be associated with a saving on additional parts, with italso being possible here to dispense with lengthy alignment of thefastening element and/or of the outflow openings.

Rapid installation is also achieved by designing the fastening elementas a separate part which can be connected to the supporting part, inparticular by pushing on, conical pressing or screwing. Firstly, simpleproduction of the separate part is possible. Secondly, the airbag unitcan thus be adapted in a simple manner to different types of gasgenerator, since only the separate fastening part has to be substituted.

A bell-shaped fastening element can have a threaded attachment and ascrew guided therein, the screw serving for the radial bracing of thegas generator which can be retained in the bell-shaped fasteningelement. The effect thus achieved is that the radial bracing alsoenables the retaining element and therefore also the airbag to be firmlypressed against the supporting element.

The fastening of the gas generator to the supporting element can befurther simplified by means of a further, annular fastening elementwhich is connected to the supporting element when, for fasteningpurposes, the gas generator can only be pushed through the annularfastening element.

In one refinement of the airbag unit, the supporting element is ofmulti-part design. Two parts of the supporting element are provided withcutouts which, arranged adjacent, form the opening of the supportingelement, it being possible for the parts of the supporting element tohave extensions which at least partially surround the gas generator.

The gas generator is advantageously of cylindrical design and has anoutflow opening provided on the circumferential surface of the cylinder.

For simple orientation of the retaining element in the airbag module, astabilizing element which is arranged between the retaining element andthe gas generator and supports the retaining element on the retainingdevice or the housing is provided.

In order to further simplify the installation and to obtain anunambiguous alignment of the airbag, the retaining element canadvantageously be fixed on the inside of the airbag. As a result, theretaining element is not able to slide to one side during the folding ofthe airbag and during the installation of the airbag in the housing.

In order to secure the retaining element, at least one fabric part canbe fastened, in particular sewn, on the inside of the airbag. In thiscase, the seams are situated in the edge region in such a manner that apocket serving to hold and fix the retaining element in place is formedbetween the fabric part and the airbag. A fastening may be omitted inone part of the edge region, for example a longitudinal or transverseedge, of the fabric part, thereby producing an opening in the pocketthrough which the retaining element can be introduced into the pocket.In one advantageous development, at least two fabric parts which haveopenings opening in an opposed manner are provided. When the two fabricparts are arranged one above the other or opposite each other, a securepocket which is secured against the retaining element sliding out canthus be formed for holding the retaining element. The retaining elementmay also be introduced into the pocket via a slot arranged in thecentral region of the fabric part. The retaining element may also besecured against sliding out by means of tabs sewn transversely over thefabric part.

The invention will be explained in greater detail below with referenceto the attached figures, in which:

FIG. 1 a shows a cross section through a cutout of an airbag unit withan airbag, a supporting element and a retaining element for fixing theairbag on the supporting element;

FIG. 1 b shows a cross section according to FIG. 1 a, the retainingelement being provided with a throughflow opening and the airbag beingprovided with an inflow opening in the region of the retaining element;

FIG. 2 a shows a cross section according to FIG. 1 b, a gas generatorhaving an outflow opening also being illustrated;

FIG. 2 b shows a development of the exemplary embodiment from FIG. 2 awith a tubular element which is arranged on the outflow opening of thegas generator;

FIG. 2 c shows a development of the exemplary embodiment from FIG. 2 awith a tubular element which is arranged on the retaining element;

FIG. 3 a shows a perspective view of an airbag unit according to FIG. 2b after installation;

FIG. 3 b shows an exploded illustration of the individual parts of anairbag module according to FIG. 3 a;

FIG. 4 shows a view of a single-part supporting element;

FIG. 4 a shows a perspective view of an airbag unit with the supportingelement from FIG. 4;

FIG. 4 b shows a perspective view of the airbag unit from FIG. 4 acontaining a packed airbag;

FIG. 4 c shows a cross section through the airbag unit from FIG. 4 b;

FIG. 5 shows a view of a two-part supporting element;

FIG. 6 shows a perspective view of an airbag unit with the supportingelement from FIG. 5;

FIG. 7 shows a cross section through an airbag unit with a stabilizingelement in the region of the retaining element;

FIG. 8 shows a cross section of an airbag unit with a supporting elementon which a holding device for an airbag is integrally formed;

FIG. 9 a shows a longitudinal section of a cutout of an airbag unit witha housing, a gas generator, a supporting element and a retaining elementfor fixing an airbag on the supporting element;

FIG. 9 b shows a cross section through the airbag unit according to FIG.9 a,

FIG. 9 c shows an exploded illustration of the individual parts of theairbag module according to FIGS. 9 a and 9 b;

FIG. 10 a shows a longitudinal section of a cutout of an airbag modulein a further embodiment with a gas generator, a housing, an airbag, asupporting element and a retaining element for fixing the airbag on thesupporting element;

FIG. 10 b shows a cross section through the airbag module according toFIG. 10 a;

FIG. 10 c shows an exploded illustration of the individual parts of theairbag module according to FIGS. 10 a and 10 b;

FIG. 11 shows a longitudinal section through an airbag module in afurther embodiment with a housing, a supporting element, an airbag and aretaining element for fastening the airbag to the supporting element anda hose clip for fastening the gas generator to the housing;

FIG. 11 b shows a cross section through the airbag module according toFIG. 11 a;

FIG. 12 a shows a longitudinal section of a cutout of an airbag modulein a further embodiment with a gas generator which is fastened via ahose clip formed integrally with the housing;

FIG. 12 b shows a cross section through the airbag module according toFIG. 12 a;

FIG. 13 a shows a longitudinal section through a further airbag modulewith a gas generator which is braced against the supporting element viaa hose clip with a threaded insert arranged on it;

FIG. 13 b shows a cross section through the airbag module according toFIG. 13 a;

FIG. 14 shows a perspective view of the inside of an airbag, with apocket which is fixed on the airbag and is intended for holding theretaining element, said pocket being closed on three sides and beingopen on one side;

FIG. 15 shows a perspective view of the inside of the airbag with twopockets for holding the retaining element;

FIG. 16 shows a perspective top view of the inside of the airbag withtwo pockets for holding the retaining element, in a further embodiment;

FIG. 17 shows a perspective top view of the inside of the airbag with apocket for holding the retaining element, said pocket having a cut inits central region;

FIG. 18 shows a perspective top view of the inside of the airbag with apocket for holding the retaining element and a tab for securing theposition of the retaining element; and

FIG. 19 shows a perspective top view of the inside of the airbag with apocket for holding the retaining element, the retaining element beingsecured against sliding out of the pocket by two tabs.

FIG. 1 a shows a cross section through an airbag unit in the region of asupporting element 2 which has an opening 20. An airbag 3, which isindicated in the inflated state in FIG. 1 a, is arranged on one side ofthe supporting element 2, i.e. next to one surface 21 of the supportingelement 2. A section 32 of the airbag 3 is guided through the opening 20in the supporting element 2 to the other side of the supporting element2 and extends there next to the other surface 22 of the supportingelement 2. A retaining element 1 in the form of a retaining plate isplaced into this airbag section 32, said retaining element reachingbehind the edge of the opening 20 in the supporting element 2 andthereby securing said airbag section 32 in a form-fitting manner againstsliding through the opening 20. When the airbag 3 is inflated, theretaining element 1 is placed against the edge of the opening 20 onaccount of the forces acting during the inflating process, thus wedgingthe airbag section 32 between the retaining element 1 and the supportingelement 2. As a result, the airbag 3 is secured in a form-fitting manneron the supporting element 2 in the region of the opening 20 by means ofthe retaining element 1.

In the exemplary embodiment according to FIGS. 1 b and 2 a, theretaining element 1 is additionally provided with a throughflow opening10 and the airbag section 32, which surrounds the retaining element 1,is provided with an inflow opening 30, both the inflow opening 30 andthe throughflow opening 10 being aligned with the opening 20 in thesupporting element 2. Furthermore, a gas generator 4 in the form of atubular gas generator with an outflow opening 40 arranged on thecircumferential surface of its cylinder is positioned in such a mannerthat the outflow opening 40 of the gas generator 4, the inflow opening30 of the airbag 30, the throughflow opening 10 of the retaining element1 and the opening 20 of the supporting element 2 are arranged one behindanother and gas emerging from the gas generator 4 can flow into theairbag 3. In this case, the retaining element 1 is positioned and heldbetween the gas generator 4 and the supporting element 2.

In a development of the exemplary embodiment from FIGS. 1 b and 2 a, thecross section illustrated in FIG. 2 b shows a tubular element 6 which isarranged in the outflow opening 40 of the gas generator 4 and protrudeswith its gas outlet 60 through the inflow opening 30 of the airbag 3,the throughflow opening 10 of the retaining element 1 and the opening 20in the supporting element 2 into the airbag 3. The tubular element 6serves, on the one hand, for blasting gas into the airbag 3 and, on theother hand, for aligning the subassemblies 1, 2, 3 and 4 illustrated inFIG. 2 b with respect to one another.

FIG. 2 c illustrates a modification of the exemplary embodiment fromFIG. 2 b, in which the tubular element 6 is fixed on the retainingelement 1 and is aligned with the outflow opening 40 of the gasgenerator 4. In this case, the retaining element 1 and the tubularelement 6 may also be of single-part design, for example by the tubularelement 6 being integrally formed on the retaining element 1.

FIG. 3 a shows a perspective illustration of an airbag module with anairbag 3, with a gas generator 4 for inflating the airbag 3 and aretaining element 1 for fastening the airbag 3 to a supporting element 2in an arrangement according to FIG. 2 b, the supporting element 2 in theform of a supporting plate being an integral component of a housing 5accommodating the gas generator 4.

The retaining element 1 is clasped by an airbag section 32, whichprotrudes through the opening 20 in the supporting element 2, to formone part and is situated on that side of the supporting element 2 whichfaces away from the folded airbag. The housing 5 is placed onto the gasgenerator 4, which is equipped with the tubular element 6, in such amanner that the tubular element 6 protrudes through the inflow opening30 of the airbag 3, the throughflow opening 10 of the retaining element1 and the opening 20 of the supporting element 2 into the airbag 3. Onthat side of the housing 5 which faces away from the supporting element2, two radially protruding flanges 51, 52 are integrally formed on saidhousing and are braced against each other by means of two screwconnections, with the result that the housing 5 surrounds the gasgenerator 4. In order to introduce the gas generator 4 into the housing5, the latter can be expanded before the screw connections in the regionof the flanges 51, 52 are tightened.

FIG. 3 b shows an exploded illustration of the airbag module from FIG. 3a. For the installation of the airbag unit, the retaining element 1 isintroduced into the airbag 3 through a discharge opening 31 therein, andthe throughflow opening 10 of the retaining element 1 is positionedcongruently with the inflow opening 30 of the airbag 3. The retainingelement 1 together with the airbag section 32 surrounding it is thenguided from outside the housing 5 through the opening 20 of thesupporting element 2 and, on the other side of the supporting element 2,is positioned in the interior of the housing 5 in such a manner that theinflow opening 30 of the airbag 3 and the opening 20 of the supportingelement 2 are aligned with the throughflow opening 10 of the retainingelement 1, bringing about a flow connection. In this case, the retainingelement has a thickness d and two edge lengths l, l′ and the supportingelement has a slot length L and a slot width B.

For the installation of the airbag module, the housing 5 is then placedonto the gas generator 4 in such a manner that the tubular element 6protrudes through the inflow opening 30 of the airbag 3, the throughflowopening 10 of the retaining element 1 and the opening 20 of thesupporting element 2 into the airbag 3.

FIG. 4 shows an illustration of a supporting element 2 as an individualpart. The supporting element 2 has as opening 20 a slot with such awidth B and such a slot length L that the retaining element 1, on theone hand when aligned vertically to the supporting element 2, can beguided through the slot 20 and, on the other hand when aligned parallelto the slot 20, reaches behind the edge of the slot 20. The two lateralend sections 9 of the supporting element 2 are connected in each casevia webs to the basic body of the supporting element 2 and serve asbending sections.

FIG. 4 a shows the supporting element 2 from FIG. 4 as part of an airbagunit. According thereto, a retaining device comprising two hose clips 7,7′ engages around the gas generator 4, the hose clips 7, 7′ havingapertures 11 for holding the supporting element 2.

The airbag section 32 together with the retaining element 1 is guidedthrough the opening 20 of the supporting element 2 and the supportingelement 2 is placed onto the gas generator 4 in such a manner that thetubular element 6 of the gas generator 4 protrudes through the inflowopening 30 of the airbag 3 into the airbag 3. Furthermore, thesupporting element 2 is positioned in such a manner that the directionof extent of the gas generator 4 and the direction of extent of theelongate supporting element 2 run along a common axis. The two hoseclips 7, 7′ are placed onto the gas generator 4 in such a manner thatthey hold the supporting element 2 in the apertures 11 in the region ofa respective connecting web, with the bending sections 9 protruding outof the apertures 11. The interlacing of the bending sections 9 enablesthe supporting element 2 to be secured in its position with respect tothe gas generator 4.

FIG. 4 b shows the perspective illustration of an airbag moduleaccording to FIG. 4 a, a receptacle 33 for the folded airbagadditionally being illustrated. Said receptacle situated on that side ofthe supporting element 2 which faces away from the gas generator 4.

FIG. 4 c shows a cross section through the module from FIG. 4 b. As canbe seen, the retaining element 1 is surrounded by an airbag section 32and is fixed in the vertical direction with respect to its plane ofextent by the supporting element 2 and the gas generator 4 and in thehorizontal direction by the tubular element 6. The tubular element 6protrudes into the airbag 3.

FIG. 5 shows a two-part supporting element 2, comprising two T-shapedparts 8, 8′ of identical design which have a respective cutout 12 and12′ at the free end of their central limb 80, 80′. If the two T-shapedparts 8, 8′ are joined together with their central limbs 80, 80′abutting to form an H-shaped part, as illustrated in FIG. 5, then thetwo central limbs 80, 80′ form a supporting element with a slot formedby the two cutouts 12, 12′ as opening of the supporting element.

One example of an airbag unit having a supporting element 2 according toFIG. 5 is illustrated in FIG. 6. The retaining element 1 is again placedinto an airbag section 32 and is placed together with the folded airbag3, which is packed in a retainer 33, onto the tubular element 6,arranged on the outflow opening 40 of the gas generator 4, and the gasgenerator 4.

The two parts 8, 8′ forming the supporting element are pushed onto thegas generator 4 in the direction of extent (axial direction) of the gasgenerator 4 in such a manner that the cutouts 12, 12′ are positioned, asshown in FIG. 5, to result in the formation of an opening of thesupporting element, through which the tubular element 6 reaches andwhich is arranged behind the retaining element 1.

FIG. 7 shows a section through an airbag module, in which, in adevelopment of the preceding exemplary embodiments, a stabilizingelement 90 for the positioning of the retaining element 1 is provided.The stabilizing element 90 is arranged in the airbag module in such amanner that it is positioned between the retaining element 1 (togetherwith the airbag section 32) and the outer wall of the gas generator 4and is supported on the supporting element 2.

FIG. 8 shows a further embodiment of an airbag module with a supportingelement 2 forming part of a housing 5, the housing 5 being designed insuch a manner that both the airbag 3 and the gas generator 4 areaccommodated in the housing, and the supporting element 2 separates thechamber provided for holding the gas generator 4 from the storage space14 which is provided for holding the airbag 3 and is formed by a holdingdevice 13 of the housing 5. A tubular element 6 is designed as part ofthe retaining element 1 and protrudes through an opening 20 of thesupporting element 2 into the airbag 3 which is arranged in the storagespace 14.

FIGS. 9 a, 9 b and 9 c show a section of an airbag module with a housing5 and a gas generator 4. The housing 5 serves to hold the folded airbag3. That side of the housing 5 which faces the gas generator 4 isdesigned as a supporting element 2 with a slot-shaped opening 20. Onesection 32 of the airbag 3 is fastened, in accordance with the principledescribed in the preceding exemplary embodiments, to the supportingelement 2 with the aid of a retaining element 1. The retaining element 1is situated on the inside of the airbag 3 and is guided in a firstorientation through the slot-shaped opening 20 of the supporting element2 and is then brought into a second orientation in such a manner thatthe airbag 3 is fixed on the supporting element 2.

A tubular element 6 is guided through the retaining element 1 and theairbag 3 in the region of an inflow opening of the airbag 3. The tubularelement 6 may also serve at the same time as a diffuser and maintain aconfiguration corresponding to the desired inflow ratios.

In the embodiment shown in FIGS. 9 a, 9 b and 9 c, the fixing of the gasgenerator 4 on the housing 5 is achieved via two fastening elements 550,800. The fastening element 550 provided in the rear end of the gasgenerator 4, which end is opposite the outflow opening 40 of the gasgenerator 4, is designed as a single part with the housing 5. Thisfastening element 550 is designed in the form of a ring through whichthe tubular gas generator 4 can be guided. In this case, a stop region41 of the gas generator 4, which region has a larger diameter than thering, prevents the gas generator 4 from sliding out of the annularfastening element 550.

On its other side which has the outflow opening 40, the gas generator 4is secured on the housing 5 by a further fastening element 800. In thiscase, the fastening element 800 is a separate part which is pushed ontothe gas generator 4 in the direction X along the axis of the gasgenerator 4. As FIG. 9 b shows, the fastening element 800 has engagementelements 801, 802 which reach under correspondingly designed retainers501, 502 of the housing 5. When the fastening element 800 is pushed in,the engagement elements 801, 802 reach under the retainer 501, 502 andtherefore fix the fastening element 800 on the housing 5. The fasteningelement 800 is fixed on the gas generator via a washer 811, which isdeposited onto a thread of the gas generator, with a nut 810.

The gas generator 4 is therefore braced between the stop element 41,which is formed in the rear region of the gas generator 4, and the nut810 between the two fastening elements 550, 800.

The fastening element 800 furthermore serves to conduct gas from the gasgenerator 4 that emerges from the outflow opening 40 into the tubularelement 6. The fastening element 800 surrounds the front part of the gasgenerator 4 and therefore also the outflow openings 40 of the gasgenerator 4. This forms a closed chamber around the outflow openings 40of the gas generator 4, said chamber leading via the tubular element 6into the airbag 3.

FIG. 9 c shows the airbag module of FIGS. 9 a and 9 b in an explodedillustration. The airbag 3, together with its retaining element 1 whichis fixed on the inside and has a throughflow opening 10, has a shapematching the housing 5. The region 32 of the airbag 3 can be guidedthrough the slot-shaped opening 20 of the supporting element 2 of thehousing 5. In this case, the retaining element 1 is guidedperpendicularly with respect to the supporting element 2 through theslot 20. The retaining element 1 is then brought into a positionparallel to the supporting element 2 and the airbag 3 is thereforesecured on the housing 5.

The tubular element 6 is inserted through the inflow opening 10 of theretaining element 1 and of the airbag 3. The separate fastening element800 is subsequently brought into engagement with the lower region of thetubular element 6 in such a manner that it reaches with its protrudingengagement elements 801 802 under the retainers 501, 502 of the housing5. The gas generator is then guided through the annular fasteningelement 550, which is designed integrally with the housing 5, and theseparate fastening element 800 until it strikes in its stop region 41against the fastening element 550. The screw connection with the nut 810and the washer 811 causes the separate retaining element 800 to bepressed onto the gas generator 4 in such a manner that an airtightchamber is formed around the outflow openings 40 of the gas generator 4,said chamber leading via the tubular element 6 into the airbag 3. Theseparate fastening element 800 is secured on the housing 5 by theengagement elements 801, 802 engaging under the retainers 501, 502.

FIGS. 10 a, 10 b and 10 c show a further embodiment of an airbag module.A housing 5 serves again for holding an airbag 3 which is secured on thehousing 5 with the aid of a retaining element 1 guided through aslot-shaped opening 20 of the supporting element 2. As already describedin FIGS. 9 a to 9 c, a gas generator 4 is secured at its rear end via anannular fastening element 550 formed integrally with the housing 5. Thefastening of the front end of the gas generator, which end has theoutflow openings 40 of the gas generator 4, differs from theabove-described manner.

In the region of the tubular element 6, a further, bell-shaped element540 is formed integrally with the housing 5. A fastening element 840 canbe introduced into this bell-shaped element 540, said fastening elementsurrounding the front region of the gas generator in such a sealingmanner that again here a chamber is formed for conducting the gasflowing out of the outflow openings 40 of the gas generator 4 via thetubular element 6 into the airbag 3. The gas generator 4 is fastenedwith the fastening element 840 via a nut 810 and a washer 811. Thefastening element 840 is of conical configuration in parts of its outerregion. The bell-shaped element 540 has an opposed conicity. Theintroduction of the fastening element 840 in the x direction along theaxis of the gas generator 4 enables the conical regions of thebell-shaped element 540 to come into engagement with the oppositelyconical regions of the fastening element 840.

Owing to the conical clamping with the fastening element 840, which issecured via the screw connection, the gas generator is therefore bracedbetween the rear bell-shaped element 550 and the front bell-shapedelement 540. The gas generator 4 is therefore reliably secured on thehousing 5.

FIGS. 11 a and 11 b show an illustration of a further airbag module. Ahousing 5 for holding the airbag 3 is again provided, the airbag 3 beingconnected to the housing 5 via a retaining part 1 secured on thesupporting element 2 in the described manner. In the embodiment shown,the retaining part 1 has an integrally formed, tubular element 16 whichserves to conduct a flow of gas from a gas generator 4 into the airbag3. The integrally formed, tubular region 16 may also be designed in theform of a diffuser.

The securing of the gas generator 4 on the housing 5 takes place herevia a separate hose clip 860 which is connected to the housing via screwconnections 861, 862. In this case, the hose clip 860 seals off anoutflow opening of the gas generator 4 that is situated at the bottom.The outflow opening of the gas generator which faces in the direction ofthe tubular region 16 remains free. The gases therefore emerge from thegas generator exclusively via the last-mentioned opening and pass viathe tubular region 16 of the retaining element into the airbag 3.

FIGS. 12 a and 12 b show a further variant of the fastening principle ofFIGS. 11 a and 11 b. An airbag 3 is again secured on the housing 5 via aretaining element 1 on the supporting element 2, which retaining elementhas a tubular region 16. A gas generator 4 is secured on the housing 5via a hose clip 58 formed integrally with the housing 5. The hose clip58 has two regions which can be expanded in relation to each other andcan be braced against each other via a screw connection 581 in such amanner that the gas generator 4 is secured. This hose clip 58 also sealsoff only an outflow opening of the gas generator 4 that is situated atthe bottom, with an additional closure stopper 583 being provided here.The route of the gases into the airbag 3 corresponds to that describedin FIGS. 11 a and 11 b.

FIGS. 13 a and 13 b show a further embodiment of an airbag module, inwhich an airbag 3 is secured in a housing 5 in the manner alreadydescribed a number of times by a retaining element 1. In this case, thehousing 5 has a recess for holding the gas generator 4, said recessholding the latter up to half of its cross section. The gas generator 4is fastened via a hose clip 58 designed as a single part with thehousing 5. The hose clip 58 may also be designed as a separatecomponent.

A threaded attachment 580 which serves to receive a threaded screw 582is provided on the hose clip 58. The threaded screw 582 presses hereagainst a region of the gas generator 4 and, in the process, engages inparticular in an outflow opening of the gas generator 4. Engagement ofthe screw 582 in an outflow opening of the gas generator 4 first of allenables the gas generator to be fixed axially and the outflow opening tobe closed. As in the description of FIGS. 11 and 12, only that outflowopening of the gas generator which faces in the direction of thethroughflow opening of the retaining element 1 remains free. If thescrew 582 is tightened, the gas generator 4 is displaced radially in thedirection of the retaining element and braced against the hose clip 58.At the same time, the airbag 3 together with the retaining element 1 isthereby clamped between the gas generator 4 and the supporting element2.

In the following FIGS. 14 to 19, various possibilities for securing theretaining element 1 on the inside of the airbag 3 are discussed. Thedrawings each show perspective top views of the inside of the airbag.The line which is drawn in in bold and is also dashed always representsthe retaining element 1 whereas thin dashed lines represent seams.

FIG. 14 shows a fabric pocket for securing the retaining element 1 onthe inside of the airbag 3. The fabric pocket has a fabric part 300which is shown on the inside of the airbag 3 and is of somewhat largerdesign in its dimensions than the retaining element 1 which is to beinserted. Those edges of the fabric part 300 which protrude when theretaining element 1 is introduced are sewn to the airbag 3 on threesides by means of a seam 310. No seam is provided on one side 320 andthe fabric pocket formed in this manner is open. The retaining element 1can be introduced through this open side 320 into the fabric pocketformed in this manner.

An opening 10 for the flow of the gas from a gas generator into theairbag interior is provided in the fabric of the airbag 3 and in thefabric 300 forming the pocket and in the retaining element 1 itself.

A second embodiment for forming a fabric pocket for holding theretaining element 1 is shown in FIG. 15. Here, two fabric parts 300 aresewn onto the airbag 3 with the aid of seams 310. In this case, theseams 310 are designed in such a manner that the respectively oppositesides 320 of the fabric parts 300 do not have any seams. Twopocket-shaped regions which open towards each other are thereforeproduced. In the exemplary embodiment shown, the fabric parts 300 ineach case cover approximately one third of the retaining element 1, sothat the central third of the retaining element 1 is not covered by afabric part.

A further embodiment is shown in FIG. 16. Two fabric parts 300 and 300′are arranged one above the other, the upper fabric part 300 havinglarger edge lengths than the fabric part 300′ situated below it. Thelower fabric part 300′ is sewn to the airbag 3 by three seams 310′ insuch a manner that a pocket open to one longitudinal side is produced.This pocket is again dimensioned in such a manner that the retainingelement 1 can be completely inserted.

The larger fabric part 300 is placed over the lower fabric part 300′ andis provided with a seam 310 in such a manner that it is likewise open ona transverse side. However, the opening of the upper pocket produced inthis manner faces away from the opening of the lower pocket. Theretaining element 1 inserted into the lower pocket is thus securedagainst sliding out.

FIG. 17 shows a further pocket which can serve for securing theretaining element 1 in the interior of the airbag 3. A fabric part 300which has larger dimensions than the retaining part 1 is again sewn ontothe airbag 3. The fabric part 300 is closed on all four sides via seams310 and in its central region has a slot 330 which serves for theinsertion of the retaining part 1 into the pocket produced in thismanner.

In a further embodiment in FIG. 18, a fabric web 300, which is somewhatlarger than the retaining element 1, is provided with a seam 320 onthree of its sides. On the longitudinal side which is still open theseam is further continued approximately up to a third, with the resultthat only approx. two thirds of the length of that region of the pocketwhich is produced which forms the retaining part is open. As a result,the retaining part 1 can be inserted into the pocket.

In order to prevent the retaining part 1 from sliding out of the pocketwhich is produced, a tab 350 is provided, said tab being sewn over thepocket which is produced and being provided in the region of the pocketopening. The tab is sewn to the airbag 3 only in two regions and is openon its longitudinal sides.

FIG. 19 shows a further embodiment for securing the retaining element 1on the airbag 3. The fabric 300 forming the pocket for holding theretaining element 1 is closed on three sides by a seam 310. Two tabs 350are sewn transversely over the pocket. The tabs 350 are sewn to theairbag 3 only in their end regions and are accordingly open on theirlongitudinal sides 360. The retaining element 1 can thus be easilyinserted into the pocket formed from the fabric 300 and is securedagainst sliding out by the tabs 350.

1. An airbag unit comprising an airbag (3), a flat supporting element(2), in front of whose one surface (21) the airbag (3) is arranged andwhich has an opening (20) for fixing the airbag (3) on the supportingelement (2), and a retaining element (1) which interacts with thesupporting element (2) in order to fix the airbag (3) thereon, onesection (32) of the airbag (3) extending through the opening (20) of thesupporting element (2) to the other side of the supporting element (2)and being retained there in front of the other surface (22) of thesupporting element (2) by means of the retaining element (1), whereinthe dimensions of the opening (20) of the supporting element (2), on theone hand, and of the retaining element (1), on the other hand, arecoordinated with one another in such a manner that the retaining element(1) can be guided through the opening (20) in a first spatialorientation and an edge region of the opening (20) prevents theretaining element (1) from being guided through in at least one secondspatial orientation of the retaining element (1).
 2. The airbag unit asclaimed in claim 1, characterized in that the airbag section (32) holdsthe retaining element (1).
 3. The airbag unit as claimed in claim 1,characterized in that the airbag section (32) is retained in aform-fitting manner on the supporting element (2) by the retainingelement (1).
 4. The airbag unit as claimed in claim 3, characterized inthat the retaining element (1) reaches behind the edge of the opening(20) of the supporting element (2).
 5. The airbag unit as claimed in inclaim 1, wherein the retaining element (1) is designed as a retainingplate which, when aligned essentially parallel to the associated surface(22) of the supporting element (2), reaches behind the edge of theopening (20) of the supporting element (2) and, when aligned essentiallyvertically with respect to the associated surface (22) of the supportingelement (2), can be guided through the opening (20) of the supportingelement (2).
 6. The airbag unit as claimed in claim 1, wherein theopening (20) of the supporting element has a slot of defined width (B)and slot length (L), and in that the retaining element (1) is designedas a retaining plate having such a thickness (D) and having such edgelengths (l, l′) that the thickness (d) of the retaining plate (1) issmaller than the width (B) of the slot (20) and at least one edge length(l, l′) of the retaining plate (1) is smaller than the slot length (L).7. The airbag unit as claimed in claim 1, wherein the retaining element(1) has a throughflow opening (10) and the airbag (3) has an inflowopening (30) in the region of the airbag section (32), said openingsinteracting with the opening (20) of the supporting element (2) to forma passage for gas.
 8. The airbag unit as claimed in claim 7, having agas generator (4) for inflating the airbag (3), characterized in thatthe outflow opening (4) of the gas generator (4) and the inflow opening(30) of the airbag (3) are positioned with respect to each other in sucha manner that the gas produced by the gas generator (4) can flow intothe airbag (3).
 9. The airbag unit as claimed in claim 7, characterizedin that, in order to position the retaining element (1) with respect tothe supporting element (2), a tubular element (6) is arranged in such amanner that the tubular element (6) protrudes through the throughflowopening (10) of the retaining element (1) and the opening (20) of thesupporting element (2).
 10. The airbag unit as claimed in claim 9,characterized in that the tubular element (6) is of hollow-cylindricaldesign.
 11. The airbag unit as claimed in claim 9, wherein the gasgenerator (4) has a tubular element (6) which is arranged on the outflowopening (40) and protrudes through the inflow opening (30) of the airbag(3), the throughflow opening (10) of the retaining element (1) and theopening (20) of the supporting element (2).
 12. The airbag unit asclaimed in claim 11, characterized in that the retaining element (1) isprovided with a tubular element (6, 16) which is arranged on thethroughflow opening (10) of the retaining element (1) and is positionedwith respect to the supporting element (2) in such a manner that itprotrudes through the opening (20) of the supporting element (2). 13.The airbag unit as claimed in claim 12, characterized in that theretaining element (1) and the tubular element (6, 16) form a single-partor a multi-part subassembly.
 14. The airbag unit as claimed in claim 8,characterized in that the supporting element (2) is part of a housing(5) which surrounds the gas generator (4) at least in some sections. 15.The airbag unit as claimed in claim 8, characterized in that amulti-part retaining device (7, 7′, 58, 540, 550, 800, 840, 860) isprovided for holding the gas generator (4).
 16. The airbag unit asclaimed in claim 15, characterized in that the retaining device (7, 7′)retains the supporting element (2), which is of essentially flat design,at a defined distance from the gas generator (4) and surrounds the gasgenerator (4) at least in some sections.
 17. The airbag unit as claimedin claim 15, characterized in that the retaining device (7, 7′) isformed by two hose clips (7, 7′) which have a means (11) for holding thesupporting element (2).
 18. The airbag unit as claimed in claim 17,characterized in that the means (11) for holding the supporting element(2) is designed as an aperture.
 19. The airbag unit as claimed in claim15, characterized in that a first hose clip (7) and a second hose clip(7′) are arranged on both sides of the outflow opening (40) of the gasgenerator (4), in that the hose clips (7, 7′) have two apertures (11)along the direction of extent of the supporting element (2), and in thatin its end sections the supporting element (2) comprises bendingsections (9) which protrude out of the apertures (11) which face awayfrom the outflow opening, it being possible for the supporting element(2) to be fixed on the hose clips (7, 7;) by the bending sections (9)being bent transversely with respect to the direction of extent of theapertures (11).
 20. The airbag unit as claimed in claim 15,characterized in that the retaining device has at least one fasteningelement (800, 840) which secures the gas generator on the supportingelement (2) and surrounds the gas generator (4) in the region of theoutflow openings (40) in such a gastight manner that a chamber leadinginto the airbag (3) is formed.
 21. The airbag unit as claimed in claim19, characterized in that the retaining device has at least onefastening element (860, 58) which secures the gas generator on thesupporting element (2) and surrounds the gas generator (4) in the regionof the outflow openings in such a gastight manner that only one outflowopening facing in the direction of a throughflow opening (10) of theretaining element (1) remains free.
 22. The airbag unit as claimed inclaim 20, characterized in that the fastening element (800, 840, 860) isdesigned as a separate part which can be connected to the supportingpart (2), in particular by pushing on, conical pressing or screwing. 23.The airbag unit as claimed in claim 20, characterized in that thefastening element (58) is of bell-shaped design and has a threadedattachment (580) and a screw (582) guided therein, the screw (582)serving for the radial bracing of the gas generator (4) which can beretained in the bell-shaped fastening element (58).
 24. The airbag unitas claimed in claim 20, characterized in that the fastening element (58)has at least one closure stopper (583) for sealing off an outflowopening of the gas generator (4).
 25. The airbag unit as claimed inclaim 20, characterized in that the retaining device has at least onefurther, annular fastening element (550) which is connected to thesupporting element (2), which serves to hold the gas generator (4) andthrough which the gas generator (4) can be pushed.
 26. The airbag unitas claimed in claim 1, characterized in that the supporting element (2)is of multi-part design.
 27. The airbag unit as claimed in claim 26,characterized in that a first part (8) and a second part (8′) of thesupporting element (2) have a respective cutout (12, 12′) and theopening (20) of the supporting element (2) is formed by the adjacentarrangement of the cutouts (12, 12′) of the two parts (8, 8′) of thesupporting element (2).
 28. The airbag unit as claimed in claim 26,characterized in that extensions (81, 81′) which at least partiallysurround the gas generator (4) are provided in each case on the twoparts (8, 8′) of the supporting element (2).
 29. The airbag unit asclaimed in claim 8, characterized in that the gas generator (4) isdesigned as a tubular gas generator and the outflow opening (40) isarranged in the circumferential surface thereof.
 30. The airbag unit asclaimed in claim 8, characterized in that the supporting element (2) hasa holding device (13) which holds the airbag (3) and forms a storagespace (14) for the airbag (3).
 31. The airbag unit as claimed in claim1, characterized in that a flat stabilizing element (11) is arranged insuch a manner that the retaining element (1) is supported on thesupporting element (2) or on an additional retaining device (7, 7′) viathe stabilizing element (90).
 32. The airbag unit as claimed in claim31, characterized in that the retaining element (1) can be fixed on theinside of the airbag (3).
 33. The airbag unit as claimed in claim 32,characterized in that at least one fabric part (300, 300′) is fastened,in particular sewn, in its edge region on the inside of the airbag (3)in such a manner that the retaining element (1) can be fixed in a pocketformed between the airbag (3) and the fabric part (300, 300′).
 34. Theairbag unit as claimed in claim 33, characterized in that the fabricpart (300, 300′) is not connected to the airbag (3) in at least part ofthe edge region (320, 320′), thus enabling the retaining element (1) inthis part of the edge region (320, 320′) to be introduced into thepocket.
 35. The airbag unit as claimed in claim 34, characterized inthat two fabric parts (300, 300′) are arranged on the airbag (3) in sucha manner that those parts of the edge region (320, 320′) which are notconnected to the airbag (3) are arranged opposite each other in such amanner that the openings of the two pockets which are produced point inopposite directions.
 36. The airbag unit as claimed in claim 35,characterized in that the two fabric parts (300, 300′) are arranged oneabove the other.
 37. The airbag unit as claimed in claim 33,characterized in that the fabric part (300) has a slot (330) for theintroduction of the retaining element (1).
 38. The airbag unit asclaimed in claim 34, characterized in that at least one tab (360) whichis connected to the airbag (3) is guided over the fabric part (300) insuch a manner that a retaining element (1) situated in the pocket issecured against sliding